STRATEGIES FOR OPERATING BLAST FURNACES UNDER HIGH ALKALI LOAD

摘要

While attempting to increase the productivity of SAIL blast furnaces, special attention was paid to tackle the problem of high alkali loading (8-10 kg/thm). Laboratory studies were conducted to determine the effect of alkali on coke reactivity. Analysis of coke samples raked out from blast furnace tuyeres indicated an increase in alkali concentration by over 300 percent. Analysis of scaffolds along the height of the furnace showed an alkali concentration 15 times greater in the lower region.Use of better raw materials with low concentration of alkalis and low ash imported coal reduced the alkali load to about 4-5 kg/thm. Operating strategies like control of RAFT within an optimum range, changes in slag regime, periodic flushing of alkalis and burden distribution techniques were developed to tackle this load of alkali. These efforts have contributed in achieving a productivity level of more than 1 .4 t/m~3/day and smoother blast furnace operation.